Serum levels of beta-carotene were measured among healthy inhabitants (671 males and 948 females) of 2 towns in Japan to determine the association between the levels and intake frequency of green-yellow vegetables. Those individuals who consumed green-yellow vegetables frequently showed higher levels of serum beta-carotene than those who ate them less often. The influences of alcohol drinking, smoking, obesity and age on serum beta-carotene levels were similarly observed for the 2 areas. The factors listed above were used for adjustment, giving a significant association between intake frequency of green-yellow vegetables and serum beta-carotene level. The proportion of the subjects who rarely consumed green-yellow vegetables was larger among smokers than among non-smokers. There was a large difference in serum beta-carotene levels between the 2 towns, which could not be explained by alcohol drinking and smoking. Women showed statistically significantly higher serum beta-carotene levels than men.